This rapidly growing Genetic Monitoring Facility is used by 20 peer-reviewed, funded investigators from 8 Research Programs using animal models in 36 research protocols. In 2003, 97.7% of the research projects utilizing this Facility were supported by peer-reviewed funding. Good genetic monitoring has become critical to the laboratory animal needs of the Fox Chase Cancer Center (FCCC) research community, as animals used in today's biomedical research must not only be free of disease, but also be well defined in terms of their genetic makeup. At present, we monitor 11 different loci located on 9 different chromosomes. We are currently maintaining 170 lines of mice for FCCC investigators and continue to add an average of one new transgenic line per month. During the past year, the Facility has performed 5,856 genetic profile tests, a 225% increase from the 1,800 performed in 1999. Service hours for genetic monitoring services have also increased dramatically, up 140% from 342 in 1999 to 821 in 2003. The daily operation of breed ng colonies is handled by personnel trained and experienced in genetic management and record-keeping. Regular review, advice and guidance is provided by Bruce Elder, Ph.D., a consultant geneticist added in March 2004 who makes quarterly visits and reviews reports and activities in all rodent colonies, and all of the breeding, production and genetic monitoring records have been computerized. These computerized records enable us to closely monitor breeding performance, pedigree lines, and utilization of the various inbred lines and strains. The ability to monitor the genome, and maintain the breeding colonies, of unique immunodeficient and transgenic mice enhances the interaction among Members of the Immunobiology Program as well as Members of the Cellular and Developmental Biology (Burch), Mintz (Tumor Cell Biology), Human Genetics (Testa, Program Leader), Developmental Therapeutics (Kruh, Smith, Weiner, Program Leader), and Cancer Prevention and Control (Clapper) Programs. Genetic Monitoring services have become a critical part of research with animals, and the need for services is expected to continue to increase 18% per year in the future. We propose adding one FTE to support this increase in Facility activities.